Scott C. Silver

The use of camera traps for estimating jaguar Panthera onca abundance and density using capture/recapture analysis

Across their range jaguars Panthera onca are important conservation icons for several reasons: their important role in ecosystems as top carnivores, their cultural and economic value, and their potential conflicts with livestock. However, jaguars have historically been difficult to monitor. This paper outlines the first applica- tion of a systematic camera trapping methodology for abundance estimation of jaguars. The methodology was initially developed to estimate tiger abundance in India. We used a grid of camera traps deployed for 2 months, identified individual animals from their pelage patterns, and estimated population abundance using capture-recapture statistical models. We applied this methodology in a total of five study sites in the Mayan

Spatial and Temporal Interactions of Sympatric Jaguars (Panthera onca) and Pumas (Puma concolor) in a Neotropical Forest

Abstract We used extensive camera-trap surveys to study interindividual interactions among individually recognizable jaguars (Panthera onca) and plain-colored pumas (Puma concolor). Timed location data from a network of 119 trap stations in the Cockscomb Basin of Belize provide the 1st evidence of interspecific avoidance calibrated against intraspecific interactions among jaguars. Camera trapping has advantages over radiotelemetry in its potential to provide data on the complete array of individuals within the study area. The 23 individually identified male jaguars showed high levels of overlap in ranges, with up to 5 different males captured at the same location in the same month. Low levels of avoidance between individuals and a high flux of individuals contributed to low consistency in home-range ownership over the long term (3 months to 2 years). Jaguars and pumas had similar nocturnal activity schedules. Both species used similar habitats within the Cockscomb Basin, indicated by a high correlation in capture rates per location between species. Apart from their overall spatial similarities, jaguars and pumas avoided using the same location at the same time. This interspecific segregation was detectable over and above the spatial and temporal segregation of individual jaguars.

Ranging behavior of translocated and established groups of black howler monkeys Alouatta pigra in Belize, Central America

Control apparatus featuring a condition sensor, a first relay responsive to a signal from the condition sensor, the first relay being in a first state in the absence of a signal from the condition sensor and being switched to a second state in response to a signal from the condition sensor, a control relay adapted to be switched between first and second states, circuitry responsive to an operation request for switching the control relay from the first state to the second state after a time interval, and clamping circuitry operative in response to the detection of the first relay in its second state during the time interval to clamp the first relay in the second state and the control relay in the first state, overriding the influence of the condition sensor on the first relay.

A Geographic Information System Method for Estimating Home Range Size

We developed a new technique to quantify home ranges by using coordinate-based data that were collected at small time intervals and entered into a Geographic Information System (GIS). We used this technique (digitized polygons [DP]) and 4 other established methods to estimate home range sizes of groups of black howler monkeys (Alouatta pigra). We calculated the size of the area used by the study groups during the study period. The DP method used all available data points, excluded lacunae within home ranges, and accounted for spread of the group. The DP estimates of home range size were compared with 4 widely used methods: minimum convex polygon (MCP), grid-cell (GC), 95% harmonic mean (HM), and 95% adaptive kernel (AK). Sizes of home ranges ranged from 1 to 62 ha. Results of all procedures were strongly correlated (P < 0.001), although each gave very different estimates of home range sizes. The DP estimates were smaller than AK (P < 0.039) and MCP (P < 0.002) estimates and consistently (although not significantly) larger than GC methods (P = 0.99). There was no statistically significant or consistent difference between DP and HM estimates. Digitized polygons required the investigator to select path width and size of lacunae to exclude, but these decisions can be based upon biological information. This method may be the most appropriate technique to determine home range size with autocorrelated location data that can be converted to day-range paths.

Shifts in Social Structure of Black Howler (Alouatta pigra) Groups Associated with Natural and Experimental Variation in Population Density

We examined variation in the group structure of black howlers (Alouatta pigra) using the adult composition of 48 social groups. We compared the structure of groups at 5 sites with different population densities and variation in group structure over time with rising population density. In addition, we examined changes in the group structure of monkeys that were translocated from an area of high population density to an area with a much lower population density. We found at low population densities, groups comprised either heterosexual pairs or a single male with two females. At high population densities groups tended to be multimale and often contained >2 adult females. We suggest the relative costs and benefits of dispersal by maturing adults varies with population density, and in Alouatta pigra results in a shift from single to multimale groups of larger size with increasing population density.

Dietary Flexibility, Behavioral Plasticity, and Survival in Fragments: Lessons from Translocated Howlers

Examining the behavioral response of howler monkeys (Alouatta pigra) to translocation may lend some insight into their ability to repopulate and persist in tropical forest fragments. In fragmented landscapes, forest patches may be large enough to sustain small numbers of individuals and social groups, but not at levels high enough for populations to persist solely in these patches. In fragmented forest landscapes, the ability to colonize unfamiliar forest patches is necessary to maintain demographic and genetic variability. In effect, translocated individuals successfully migrate to another fragment and have to depend upon their ability to include novel food items and strata. Survival depends on the level of dietary flexibility and behavioral plasticity.

Abundance/Density Case Study: Jaguars in the Americas

Since camera traps were first used to estimate the density of tiger Panthera tigris populations in India (Karanth 1995; see also Karanth et al. this volume), this methodology has been widely used to study a variety of species: leopards Panthera pardus (Henschel and Ray 2003; Karanth et al. this volume; Kostyria et al. 2003), snow leopards Panthera uncia (Jackson et al. 2006), pumas Puma concolor (Kelly et al. 2008), ocelots Leopardus pardalis (Di Bitetti et al. 2006, 2008; Dillon and Kelly 2007, 2008; Maffei et al. 2005; Trolle and Kery 2003, 2005), and Geoffroy’s cats Oncifelis geoffroyi (Cuellar et al. 2006; Pereira et al. 2006). However, jaguars Panthera onca have probably received the most attention with respect to using camera traps to estimate the abundance and density of populations that cover the species’ entire Neotropical range (Cullen et al. 2005; Kelly 2003; Maffei et al. 2004b; Miller and Miller 2005; Silver et al. 2004; Soisalo and Cavalcanti 2006). To date, at least 83 different camera trapping efforts have been carried out to survey jaguars, from southern Arizona in the north to northern Argentina in the south. In this chapter, we describe the details of this methodology – summarizing information on survey design and methodologies, results, data manipulation and analyses – and discuss how future surveys can be refined to allow for more robust inferences.

Long term monitoring of jaguars in the Cockscomb Basin Wildlife Sanctuary, Belize; Implications for camera trap studies of carnivores

In this study, we estimate life history parameters and abundance for a protected jaguar population using camera-trap data from a 14-year monitoring program (2002–2015) in Belize, Central America. We investigated the dynamics of this jaguar population using 3,075 detection events of 105 individual adult jaguars. Using robust design open population models, we estimated apparent survival and temporary emigration and investigated individual heterogeneity in detection rates across years. Survival probability was high and constant among the years for both sexes (φ = 0.78), and the maximum (conservative) age recorded was 14 years. Temporary emigration rate for the population was random, but constant through time at 0.20 per year. Detection probability varied between sexes, and among years and individuals. Heterogeneity in detection took the form of a dichotomy for males: those with consistently high detection rates, and those with low, sporadic detection rates, suggesting a relatively stable population of ‘residents’ consistently present and a fluctuating layer of ‘transients’. Female detection was always low and sporadic. On average, twice as many males than females were detected per survey, and individual detection rates were significantly higher for males. We attribute sex-based differences in detection to biases resulting from social variation in trail-walking behaviour. The number of individual females detected increased when the survey period was extended from 3 months to a full year. Due to the low detection rates of females and the variable ‘transient’ male subpopulation, annual abundance estimates based on 3-month surveys had low precision. To estimate survival and monitor population changes in elusive, wide-ranging, low-density species, we recommend repeated surveys over multiple years; and suggest that continuous monitoring over multiple years yields even further insight into population dynamics of elusive predator populations.